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Audio-Signal Time-Axis Expansion/Compression Method and Device

Inactive Publication Date: 2007-10-25
SONY CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0039] According to an embodiment of the present invention, employing a first period and a second period which are continuous and similar within an audio signal, and generating a cross-fade signal by using a correction signal wherein the difference signal between a first period signal and a second period signal is subjected to time-axis reversal, whereby surge-like allophone can be reduced.

Problems solved by technology

However, with the existing PICOLA, though excellent sound quality can be obtained as to a speech signal, it is difficult to obtain excellent sound quality as to an acoustic signal such as music or the like, which causes a problem in some cases.

Method used

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  • Audio-Signal Time-Axis Expansion/Compression Method and Device
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  • Audio-Signal Time-Axis Expansion/Compression Method and Device

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first embodiment

[0075]FIG. 1 is a block diagram illustrating the configuration of an audio-signal time-axis expansion / compression device according to a first embodiment of the present invention.

[0076] An audio-signal time-axis expansion / compression device 10 is configured with an input buffer 11 for subjecting an input audio signal to buffering, a similar-waveform-length extracting unit 12 for extracting a continuous similar waveform length (equivalent to 2 W samples) from the audio signal of the input buffer 11, a connection-waveform generating unit 13 for subjecting the audio signals of 2 W samples to cross-fade to generate the connection waveforms of W samples, and an output buffer 14 for outputting an output signal made up of the input audio signal input in accordance with a speech rate conversion rate R, and a connection waveform. An input audio signal to be processed is subjected to buffering to the input buffer 11.

[0077] The similar-waveform-length extracting unit 12 determines periods A a...

second embodiment

[0127] Next, description will be made regarding a second embodiment to which the present invention is applied. With the first embodiment, a cross-fade signal is generated with first and second periods which are continuous and similar within an audio signal, the difference signal between a first period signal and a second period signal is subjected to time-axis reversal, and is multiplied by a window function to generate a time-axis reversal difference signal serving as a correction signal, and the cross-fade signal and the correction signal are added to generate a connection waveform, but with the second embodiment, the signal obtained by subjecting the difference signal between a first period and a second period to time-axis reversal is added to the sum signal of the first period and the second period to generate a cross-fade signal,

[0128] An audio-signal time-axis expansion / compression device 20 according to the second embodiment is the same as the audio-signal time-axis expansio...

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Abstract

An audio-signal time-axis expansion / compression method for subjecting an audio signal to time-axis expansion / compression at a time domain includes the steps of: cross-fade-signal generating wherein a first period and a second period which are similar within the audio signal are employed to generate the cross-fade signal of the first period signal and the second period signal; correction-signal generating wherein the difference signal between the first period signal and the second period signal is subjected to time-axis reversal, and is multiplied with a window function to generate a correction signal; and connection-waveform generating wherein the cross-fade signal and the correction signal are added to generate a connection waveform for subjecting the audio signal to time-axis expansion / compression at the time domain.

Description

CROSS REFERENCES TO RELATED APPLICATIONS [0001] The present invention contains subject matter related to Japanese Patent Application JP 2006-119731 filed in the Japanese Patent Office on Apr. 24, 2006, the entire contents of which are Incorporated herein by reference. BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] The present invention relates to an audio-signal time-axis expansion / compression method and device for changing the playback speed of music or the like. [0004] 2. Description of the Related Art [0005] The PICOLA (Pointer Interval Control Overlap and Add) serving as a time-axis expansion / compression algorithm at a time domain corresponding to a digital speech signal has been known (see “Expansion / compression on the audio time-axis using the duplication adding method by pointer amount-of-movement control (PICOLA) and its evaluation”, by Morita and Itakura, Acoustical Society of Japan collected papers, October 1986, pp 149-150). This algorithm has an adva...

Claims

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Application Information

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IPC IPC(8): G10L21/04G10L21/049
CPCG10L21/04
Inventor NAKANURA, OSAMUABE, MOTOTSUGUNISHIGUCHI, MASAYUKI
Owner SONY CORP